The reproducing alumina-magnesia-carbon bricks were prepared with the dumped bricks as starting materials. The bulk density, apparent porosity, crushing strength, modolus of rupture and slag resistance of the specimen...The reproducing alumina-magnesia-carbon bricks were prepared with the dumped bricks as starting materials. The bulk density, apparent porosity, crushing strength, modolus of rupture and slag resistance of the specimen were analyzed. The results show that the used refractories can be reused and recycled by the right method. The reproducing alumina-magnesia-carbon bricks with better abilities were prepared.展开更多
In order to reduce the cost and to improve the low temperature bonding strength of phenol formaldehyde resin（ PF）,the lignin modified phenol formaldehyde resin（ LPF） was synthesized using calcium lignosulfonate as...In order to reduce the cost and to improve the low temperature bonding strength of phenol formaldehyde resin（ PF）,the lignin modified phenol formaldehyde resin（ LPF） was synthesized using calcium lignosulfonate as a partial replacement of phenol,and sodium hydroxide as catalyzer. Then the magnesia carbon bricks were prepared using the LPF as binder. Different process conditions of LPFs such as calcium lignosulfonate additions（ 10%,20%,30%,40% and 50%,in mass,the same hereinafter）,catalyzer additions（ extra added,1%,2%,3%,4% and 5%） and reaction times（ 1,1. 5,2,2. 5 and 3 h） were investigated. Effects of prepared LPFs on properties of magnesia carbon bricks（ baked at 200 ℃ for 24 h） were researched in order to modify the synthesizing conditions of LPFs. Cold physical properties and hot modulus of rupture of magnesia carbon bricks bonded by LPF and by traditional PF after baked at 200 ℃ for 24 h and fired at 1 200 ℃ for 3 h were compared,respectively. The results show that the optimal synthesizing conditions of LPF for preparing magnesia carbon bricks are 30% calcium lignosulfonate,1% catalyzer,and 2 h reaction time. The magnesia carbon bricks bonded by the optimal LPF achieve：（ 1） the bulk densities 2. 84 g · cm- 3and 2. 82g·cm- 3,apparent porosities 9. 6% and 14. 6%,moduli of rupture 17. 8 MPa and 6. 4 MPa,crushing strengths72. 3 MPa and 48. 7 MPa,after baked at 200 ℃ and1 200 ℃,respectively;（ 2） the hot modulus of rupture7. 3 MPa after fired at 1 400 ℃. The above properties are better than those of the magnesia carbon brick bonded by PF.展开更多
1 Scope This standard specifies the classification, technical requirements, test methods, quality appraisal procedures, packing, marking, transportation, storage, and quality certificate of magnesia carbon bricks.
1 Scope This standard specifies the classification, technical requirements, test method, inspection rules, marking, packing, transportation and storage of magnesia carbon brick.
Magnesium aluminate spinel -corundum composite was prepared with waste slide plate and magnesia carbon brick. Microstructure and sintering ability of as-prepared magnesium aluminate spinel -corundum composite were inv...Magnesium aluminate spinel -corundum composite was prepared with waste slide plate and magnesia carbon brick. Microstructure and sintering ability of as-prepared magnesium aluminate spinel -corundum composite were investigated with XRD, SEM, and DSC/TG. With the addition of waste slide plate increasing or synthesis tem- perature rising, the bulk density of the specimen increases and the apparent porosity decreases, but the crystallinity of the specimen decreases and the magnesium alaminate spinel phase increases. The obtained composite contains 72% spinel and 26% corundum. Primary phase and secondary phase are bonded by glass phase. The results show that it is feasible to synthesis magnesium aluminate spinel - corundum material with waste slide plate and magnesia carbon brick.展开更多
Conventional resin bonded MgO-C bricks, which are manufactured via cold mixing process, harden and attain brittleness during carbonization of resin due to the formation of isotropic glassy carbon. They do not exhibit ...Conventional resin bonded MgO-C bricks, which are manufactured via cold mixing process, harden and attain brittleness during carbonization of resin due to the formation of isotropic glassy carbon. They do not exhibit thermo-plasticity, which can facilitate the release of huge amount of stresses generated during preheating or in operation. On the contrary, pitch bonded MgO-C bricks, show better pyro-plasticity due to formation of an anisotropic and graphitized coke structure during carbonization of pitch. Hence, pitch bonded bricks show a superior structural spalling resistance in comparison to resin-bonded bricks. One of the drawbacks of pitch-bonded bricks is that the manufacturing requires a hot mixing process and hot pressing facility. This paper describes how a combination of above two processes was optimized to make a MgO-C brick via cold process. These bricks exhibit a low Modulus of Elasticity and thereby facilitate release of stresses during operation. Normal coal tar pitch is considered as an environmental hazard due to the presence of polyaromatic hydrocarbons like benzopyrene B [ a ] P. So, a special binder with a low B[ a ] P was selected, which is eco-friendly in nature. Such bricks were made in our plant in China and supplied to an integrated steel plant in Europe for their ladle. The bricks supplied have given encouraging life.展开更多
The service life of a blast furnace depends largely on the degree of damage to the carbon brick in the hearth.Carbon brick and ramming material in the hearth of a 1780 m3 blast furnace after shutdown were sampled and ...The service life of a blast furnace depends largely on the degree of damage to the carbon brick in the hearth.Carbon brick and ramming material in the hearth of a 1780 m3 blast furnace after shutdown were sampled and investigated.It was found that the substances in the cracks of the carbon brick near and above the taphole were ZnO and Zn_(2)SiO_(4),whereas the substances in the cracks of the carbon brick below the taphole were ZnS.The reaction of Zn with CO,SiO_(2),and Fes generates ZnO,Zn_(2)SiO_(4),and ZnS,resulting in volume expansion,which is an important reason for the cracking of carbon brick.Simultaneously,several obvious Zn vapor flow channels were found in the ramming material,through which Zn vapor could enter the carbon brick,causing damage to the carbon brick.Increasing the compactness of the ramming material is beneficial to preventing Zn vapor from entering the carbon brick through the voids in the ramming material,reducing the destructive effect of Zn on the carbon brick and further extending the service life of the blast furnace.展开更多
Low-carbon MgO - C specimens with dimension of Ф6 mm × 36 mm were prepared using fused magnesia, flake graphite and carbon black as main starting materials, thermoplastic phenolic resin as binder, hexamethyl ene...Low-carbon MgO - C specimens with dimension of Ф6 mm × 36 mm were prepared using fused magnesia, flake graphite and carbon black as main starting materials, thermoplastic phenolic resin as binder, hexamethyl ene tetramine as curing agent, Si powder （ w （Si） 〉 80%, particle size 〈0. 074 mm） and B℃ （ d90 =36. 5 μm ） as antioxidant, pressing under 200 MPa and drying at 200 ℃ for 24 h. The oxidation resistance tests were conducted at 600 ℃ , 1 000 ℃ and 1 400 ℃ for 2 h, respectively. Effects of B4C and Si antioxidant on oxidation resistance of low-carbon MgO - C brick were studied by comparing the areas of the decarburized layers. The results shaw that： （1） When Si powder addition is 3%, at 600 ℃ and 1 000 ℃, the specimens with 0. 5% B4C perform good oxidation resistance; at 1 400 ℃, the oxidation resistance of the specimens is improved with the addition of B4C increasing, and that of the specimen with 0. 7% B4 C is the best. （2） When B4C addition is 0. 5%, at 600 ℃ and 1 000 ℃ ,the oxidation resistances of the specimens with 3% and 5% Si powder are similar, which are better than that of the specimen with 1% Si powder; and at 1 400 ℃ , the oxidation resistance of the specimens is improved obviously with the addition of Si powder increasing, and that of the specimen with 5% Si powder is the best. （3） Bused on the results, it is believed that the low-carbon MgO - C brick with 0. 5% B4C and 3% Si powder performs the best oxidation resistance.展开更多
The properties of the carbonated brick made of steel slag-slaked lime mixture such as strength, drying shrinkage, water absorption and soundness were mainly investigated. The experimental results indicate that, after ...The properties of the carbonated brick made of steel slag-slaked lime mixture such as strength, drying shrinkage, water absorption and soundness were mainly investigated. The experimental results indicate that, after carbonation, the strength of the brick increases, its drying shrinkage reduces, and its soundness becomes eligible. The optimal slaked lime/steel slag（SL/SS） ratio for the carbonated brick is 0.2 and the asprepared brick meets the requirements of the Chinese standard for MU20-grade building bricks, additionally, it also demonstrates prominent environmental benefits. The XRD and pore structure analyses indicate that the excellent properties of this carbonated brick are attributed to the formation of carbonate crystals and the dense structure due to the carbonation.展开更多
The effect of Ti （ C, N） on properties of low-carbon MgO - C bricks was investigated. The phase composition and the microstructure of the matrix of low-carbon MgO - C brick containing Ti （ C, N） were studied by XR...The effect of Ti （ C, N） on properties of low-carbon MgO - C bricks was investigated. The phase composition and the microstructure of the matrix of low-carbon MgO - C brick containing Ti （ C, N） were studied by XRD and SEM analysis together with EDS. The results showed that Ti （ C, N） distributed in the matrix of lowcarbon MgO - C brick uniformly after being treated at 1 600 ~C for 3 h in coke powder bed, and Ti （C, N） and MgO formed a solid solution. After the treatment at 1 600 ℃ for 3 h in coke powder bed, the bulk density and cold crushing strength of low-carbon MgO - C brick with Ti （ C, N） decreased, and the apparent porosity and linear change rate of specimens increased. The oxidation resistance of low-carbon MgO - C brick with Ti（ C, N） was superior to that of low-carbon MgO - C brick with no additives, but inferior to that of low-car- bon MgO - C brick with Al powder. The slag resistance of the specimen with Ti （ C, N） was excellent as well.展开更多
The effects of graphite granularity on the properties of low carbon MgO-C based materials have been investigated in the work. Large crystal fused magnesia, natural flake graphite with different particle sizes and anti...The effects of graphite granularity on the properties of low carbon MgO-C based materials have been investigated in the work. Large crystal fused magnesia, natural flake graphite with different particle sizes and anti-oxidant were adopted as raw material for preparation of specimens. However, the results show that the physical properties, oxidation resistance and thermal shock resistance of low carbon MgO-C materials with content of 4.0wt% graphite are improved obviously through the use of special and suitable size graphite. The excellent performance achieved was considered as a result of microstructure modification of MgO-C materials. Therefore, it is suggested that both fine and micro grade natural flake graphite used for production of low carbon MgO-C bricks.展开更多
An environmental friendly carbonaceous material- carboresP （one of the Carbores series materials） was investigated for the production of MgO-C refractories in laboratory scale and field tests. The MgO-C specimens we...An environmental friendly carbonaceous material- carboresP （one of the Carbores series materials） was investigated for the production of MgO-C refractories in laboratory scale and field tests. The MgO-C specimens were produced with different CarboresP contents. The bulk density （180℃ × 48h）, CCS, apparent porosity （1000℃ ×3h ） and hot modulus of rupture （1400℃ ×0. 5h ） were tested and contrasted. The appropriate amount of carboresP was 1.0%. The amount of metallic additions can be partially substituted （reduced to 1.5% ）. The microstructure of resin-carboresP binder is anisotropic structure with high oxidation resistance and good thermal-shock stability. The Stress/strain curve indicates that the characteristic length, （LCH） of MgO-C brick with resin/CarboresP bonding has been improved, which means the MgO-C bricks have good mechanical flexibility and stresses absorbability. Field tests were done in slag line of a 40t LF-VD refining steel ladle using Resin/CarboresP bonded ＂ MT-14A MgO-C bricks. The result shows that the MgO-C bricks by ＂soft bonding＂ have good physical properties and excellent workability during production of the bricks . In contrast with traditional MgO-C brick used for secondary refining furnaces, the spalling tendency of the bricks could be reduced significantly. The average lining life of the resin/ CarboresP bricks has increased by 18. 4% comparing with the pure resin-bonded types.展开更多
Resins PFG-4 , PFG-8 and a reference resin （resin A） were used as binders of MgO - C bricks, effects of the resins with different molecular structures on wettability of magnesia, on physical properties, mechanical p...Resins PFG-4 , PFG-8 and a reference resin （resin A） were used as binders of MgO - C bricks, effects of the resins with different molecular structures on wettability of magnesia, on physical properties, mechanical properties, oxidation resistance and thermal expansion properties of MgO- C bricks were researched. The results show that the microstructures of solidified resins with different mo- lecular structures are different, which have obvious effect on the cold mechanical properties of MgO - C brick, but little effect on the oxidation resistance, thermal perform- ance and expansion properties.展开更多
Properties, section structure and service results of recycled MgO-C bricks and new MgO-C bricks for ladle slag line of Baosteel were analyzed and compared, and the measures of improving stability and quality of recycl...Properties, section structure and service results of recycled MgO-C bricks and new MgO-C bricks for ladle slag line of Baosteel were analyzed and compared, and the measures of improving stability and quality of recycled MgO-C bricks were summarized. The results show that： （1） High quality recycled MgO-C materials can be produced by scientific, meticulous and strict management for every process such as dismantling furnace, selection, removing impurity and slag, stacking and homogenization ; （2） Using high quality recycled materials and reasonable production technique, recycled MgO-C bricks with better properties and service efficiency than those of new MgO-C brick can be produced; （3） Service efficiency of recycled MgO - C bricks is good because of its high density, good oxidation resistance and reasonable structure.展开更多
Hot metal transfer ladles were historically lined with high alumina refractories because of compatibility of high alumina refractories with the highly acidic slag, which is transferred .from the iron making plant alon...Hot metal transfer ladles were historically lined with high alumina refractories because of compatibility of high alumina refractories with the highly acidic slag, which is transferred .from the iron making plant along with hot metal. With the introduction of higher capacity ladles, technological advancement in the process and increased productivity, calls for a higher campaign life of hot metal ladles, which could not be performed by ordinary high alumina refractories. Resin bonded Al2O3- SiC-C （hereinafter ASC ） bricks gradually developed which at present taking place replacing the conventional refractories. Considerable work has been carried out in developing the ASC refractory to reach the present state. However, for higher capacity ladles still there is a lot of scope for improvement. The present paper deals with the newly developed ASC bricks, which was used in 165 ton capacity hot metal ladles in one European plant and has given a substantial increase in performance. But, the customer was not fuUy satisfied since the brick was reported to produce smokes during preheating of the ladle. In the subsequent supply the smoke generation problem was taken care by adjusting the binders and additives and eco-friendly bricks were re-engineered and supplied to the same plant, which also performed splendidly and created all time record in their plant history.展开更多
Al2O3-SiC-C specimens were prepared using white fused corundum （3-1,≤1 and ≤0.044 mm）,Al2O3-SiC composite powders （d50 ≤ 5 μm）,α-Al2O3 micropowder （d50 =1.2 μm）,SiC powder （≤ 0.044 mm）,flake graphite （...Al2O3-SiC-C specimens were prepared using white fused corundum （3-1,≤1 and ≤0.044 mm）,Al2O3-SiC composite powders （d50 ≤ 5 μm）,α-Al2O3 micropowder （d50 =1.2 μm）,SiC powder （≤ 0.044 mm）,flake graphite （≤ 0.088 mm）,Si powder （d50 =42.8 μm） and B4C powder （d50 ≤10 μm） as main starting materials,and thermosetting phenolic resin as binder.4%,8%,12% and 16% （in mass,the same hereinafter） of Al2O3-SiC composite powders substituted the same quantity of α-Al2O3 micropowder ＋ SiC powder.Effects of composite powder additions on apparent porosity,bulk density,cold modulus of rupture,cold crushing strength,hot modulus of rupture （1 400 ℃）,thermal shock resistance （1 100 ℃,water quenching） and oxidation resistance （1 000 and 1 500 ℃） of Al2O3-SiC -C specimens after 180 ℃ curing,1 000 ℃ 3 h carbon-embedded firing and 1 500 ℃ 3 h carbon-embedded firing,respectively,were researched.The results indicate that：（1） with the increase of Al2O3-SiC composite powder,cold strengths of the cured specimens decline,those of the specimens fired at 1 000 ℃ change a little,and those of the specimens fired at 1 500 ℃ change a little except for an obvious improvement of cold crushing strength ; （2） with the increase of Al2O3-SiC composite powder,hot modulus of rupture at 1 400 ℃ decreases and thermal shock resistance enhances significantly; （3） when Al2O3-SiC composite powder addition is 4%,the oxidation resistance at 1 500 ℃ is the best,and the reason may be the composite powder is finer and more active,which is beneficial to form dense mullite protective layer to retard the O2 diffusion into the specimens.展开更多
In some steel making workshops, the existed inher- ent weaknesses of traditional carbon containing brick working lining, such as joint opening, vertical cracking of lining, and excessive erosion of brick edge, made it...In some steel making workshops, the existed inher- ent weaknesses of traditional carbon containing brick working lining, such as joint opening, vertical cracking of lining, and excessive erosion of brick edge, made it hard to satis]~ the demands of advanced steel produc- tion. A new-type carbon free corundum spinel brick and castable were developed based on the matrix optimized analysis, successfully applied for ultra-low carbon steel production. The advantages of the newly developed car- bon free working lining are mainly as follows： I ） the inherent weaknesses of joint opening, vertical cracking of lining, excessive erosion of brick edge, etc. are sur- mounted successfully, which improves the operational safety of ladles; 2 ） the outer temperature of the ladle shell decreases by 45 -50 ℃ compared with that of the traditional carbon containing brick lining; 3） the service life of new-type working lining is 150 -170 heats, near- ly doubling that of the traditional carbon containing brick lining; the specific eonaumption of refractories per ton steel decreases by about 20% ; 4） the carbon pickup of mohen steel is not obvious which is merely 5 - 10 ppm, which satisfies the demands of low ＆ ultra low carbon steel production.展开更多
Aiming at improving the properties of magnesia carbon materials,silicon aluminum carbide(Al_(4)SiC_(4))containing materials were prepared using industrial aluminum powder,silicon carbide powder,and graphite as raw mat...Aiming at improving the properties of magnesia carbon materials,silicon aluminum carbide(Al_(4)SiC_(4))containing materials were prepared using industrial aluminum powder,silicon carbide powder,and graphite as raw materials,and activated alumina powder as an additive,mixing thoroughly,pressing into cylinders and then firing at 1200℃for 30 min in a carbon embedded atmosphere by the microwave method.The effects of the aluminum powder addition(20%and 24%,by mass)and activated alumina powder addition(0,3%,5%and 7%,by mass)on the microwave synthesis of Al_(4)SiC_(4) as well as the effect of the obtained Al_(4)SiC_(4) containing material on the properties of magnesia carbon bricks were studied.The results show that:compared with the samples with 20%aluminum powder,those with 24%aluminum powder generate more Al_(4)SiC_(4).With the activated alumina powder addition increasing from 0 to 7%,the amount of Al_(4)SiC_(4) generated increases first and then decreases.Compared with the sample without activated alumina powder,the samples with activated alumina powder show lower bulk density and higher apparent porosity.With the activated alumina powder addition increasing from 3%to 7%,the bulk density of the samples increases first and then decreases,while the apparent porosity of the samples shows an opposite trend.The optimal additions are 24%aluminum powder and 5%activated alumina powder,and Al_(4)SiC_(4) synthesized in this sample has a hexagonal plate structure.With the synthesized Al_(4)SiC_(4) containing material added,the magnesia carbon brick has slightly increased cold modulus of rupture,basically the same modulus of elasticity and improved oxidation resistance.展开更多
The study was conducted to evaluate the changes in soil properties due to the impacts of brick kiln in the vicinity of the Kirtonkhola River, Barisal. The study was carried out by determining the physical, physico-che...The study was conducted to evaluate the changes in soil properties due to the impacts of brick kiln in the vicinity of the Kirtonkhola River, Barisal. The study was carried out by determining the physical, physico-chemical and chemical characteristics of soil. During the entire study period, moisture content of soil ranged from 18.77% to 56.49%;bulk density and particle density varies from 0.23 - 0.53 g/cm3 and 1.11 - 3.15 g/cm3, respectively;soil porosity varies from 60.36% to 88.14%;pH varies from 6.98 to 8.85 and organic carbon content varies from 0.22% to 1.4%. The finding revealed that the pH of the soil decreased with increasing distance from the kiln;moisture content and organic carbon increased with distance;particle density was more or less in ideal condition for plant growth but bulk density and porosity indicates poor soil structure which is unfavourable for plant.展开更多
文摘The reproducing alumina-magnesia-carbon bricks were prepared with the dumped bricks as starting materials. The bulk density, apparent porosity, crushing strength, modolus of rupture and slag resistance of the specimen were analyzed. The results show that the used refractories can be reused and recycled by the right method. The reproducing alumina-magnesia-carbon bricks with better abilities were prepared.
基金New Century Excellent Talents Program of Ministry of Education ( NCET - 09 - 0137 )The open foundation of the State Key Laboratory of Refractories and Metallurgy ( 2014QN17 )
文摘In order to reduce the cost and to improve the low temperature bonding strength of phenol formaldehyde resin（ PF）,the lignin modified phenol formaldehyde resin（ LPF） was synthesized using calcium lignosulfonate as a partial replacement of phenol,and sodium hydroxide as catalyzer. Then the magnesia carbon bricks were prepared using the LPF as binder. Different process conditions of LPFs such as calcium lignosulfonate additions（ 10%,20%,30%,40% and 50%,in mass,the same hereinafter）,catalyzer additions（ extra added,1%,2%,3%,4% and 5%） and reaction times（ 1,1. 5,2,2. 5 and 3 h） were investigated. Effects of prepared LPFs on properties of magnesia carbon bricks（ baked at 200 ℃ for 24 h） were researched in order to modify the synthesizing conditions of LPFs. Cold physical properties and hot modulus of rupture of magnesia carbon bricks bonded by LPF and by traditional PF after baked at 200 ℃ for 24 h and fired at 1 200 ℃ for 3 h were compared,respectively. The results show that the optimal synthesizing conditions of LPF for preparing magnesia carbon bricks are 30% calcium lignosulfonate,1% catalyzer,and 2 h reaction time. The magnesia carbon bricks bonded by the optimal LPF achieve：（ 1） the bulk densities 2. 84 g · cm- 3and 2. 82g·cm- 3,apparent porosities 9. 6% and 14. 6%,moduli of rupture 17. 8 MPa and 6. 4 MPa,crushing strengths72. 3 MPa and 48. 7 MPa,after baked at 200 ℃ and1 200 ℃,respectively;（ 2） the hot modulus of rupture7. 3 MPa after fired at 1 400 ℃. The above properties are better than those of the magnesia carbon brick bonded by PF.
文摘1 Scope This standard specifies the classification, technical requirements, test methods, quality appraisal procedures, packing, marking, transportation, storage, and quality certificate of magnesia carbon bricks.
文摘1 Scope This standard specifies the classification, technical requirements, test method, inspection rules, marking, packing, transportation and storage of magnesia carbon brick.
文摘Magnesium aluminate spinel -corundum composite was prepared with waste slide plate and magnesia carbon brick. Microstructure and sintering ability of as-prepared magnesium aluminate spinel -corundum composite were investigated with XRD, SEM, and DSC/TG. With the addition of waste slide plate increasing or synthesis tem- perature rising, the bulk density of the specimen increases and the apparent porosity decreases, but the crystallinity of the specimen decreases and the magnesium alaminate spinel phase increases. The obtained composite contains 72% spinel and 26% corundum. Primary phase and secondary phase are bonded by glass phase. The results show that it is feasible to synthesis magnesium aluminate spinel - corundum material with waste slide plate and magnesia carbon brick.
文摘Conventional resin bonded MgO-C bricks, which are manufactured via cold mixing process, harden and attain brittleness during carbonization of resin due to the formation of isotropic glassy carbon. They do not exhibit thermo-plasticity, which can facilitate the release of huge amount of stresses generated during preheating or in operation. On the contrary, pitch bonded MgO-C bricks, show better pyro-plasticity due to formation of an anisotropic and graphitized coke structure during carbonization of pitch. Hence, pitch bonded bricks show a superior structural spalling resistance in comparison to resin-bonded bricks. One of the drawbacks of pitch-bonded bricks is that the manufacturing requires a hot mixing process and hot pressing facility. This paper describes how a combination of above two processes was optimized to make a MgO-C brick via cold process. These bricks exhibit a low Modulus of Elasticity and thereby facilitate release of stresses during operation. Normal coal tar pitch is considered as an environmental hazard due to the presence of polyaromatic hydrocarbons like benzopyrene B [ a ] P. So, a special binder with a low B[ a ] P was selected, which is eco-friendly in nature. Such bricks were made in our plant in China and supplied to an integrated steel plant in Europe for their ladle. The bricks supplied have given encouraging life.
基金financially supported by the National Natural Science Foundation of China(62071034).
文摘The service life of a blast furnace depends largely on the degree of damage to the carbon brick in the hearth.Carbon brick and ramming material in the hearth of a 1780 m3 blast furnace after shutdown were sampled and investigated.It was found that the substances in the cracks of the carbon brick near and above the taphole were ZnO and Zn_(2)SiO_(4),whereas the substances in the cracks of the carbon brick below the taphole were ZnS.The reaction of Zn with CO,SiO_(2),and Fes generates ZnO,Zn_(2)SiO_(4),and ZnS,resulting in volume expansion,which is an important reason for the cracking of carbon brick.Simultaneously,several obvious Zn vapor flow channels were found in the ramming material,through which Zn vapor could enter the carbon brick,causing damage to the carbon brick.Increasing the compactness of the ramming material is beneficial to preventing Zn vapor from entering the carbon brick through the voids in the ramming material,reducing the destructive effect of Zn on the carbon brick and further extending the service life of the blast furnace.
文摘Low-carbon MgO - C specimens with dimension of Ф6 mm × 36 mm were prepared using fused magnesia, flake graphite and carbon black as main starting materials, thermoplastic phenolic resin as binder, hexamethyl ene tetramine as curing agent, Si powder （ w （Si） 〉 80%, particle size 〈0. 074 mm） and B℃ （ d90 =36. 5 μm ） as antioxidant, pressing under 200 MPa and drying at 200 ℃ for 24 h. The oxidation resistance tests were conducted at 600 ℃ , 1 000 ℃ and 1 400 ℃ for 2 h, respectively. Effects of B4C and Si antioxidant on oxidation resistance of low-carbon MgO - C brick were studied by comparing the areas of the decarburized layers. The results shaw that： （1） When Si powder addition is 3%, at 600 ℃ and 1 000 ℃, the specimens with 0. 5% B4C perform good oxidation resistance; at 1 400 ℃, the oxidation resistance of the specimens is improved with the addition of B4C increasing, and that of the specimen with 0. 7% B4 C is the best. （2） When B4C addition is 0. 5%, at 600 ℃ and 1 000 ℃ ,the oxidation resistances of the specimens with 3% and 5% Si powder are similar, which are better than that of the specimen with 1% Si powder; and at 1 400 ℃ , the oxidation resistance of the specimens is improved obviously with the addition of Si powder increasing, and that of the specimen with 5% Si powder is the best. （3） Bused on the results, it is believed that the low-carbon MgO - C brick with 0. 5% B4C and 3% Si powder performs the best oxidation resistance.
基金Funded by the"Eleventh Five-year Plan"for Sci&Tech Research of China(NO.2006BAF02A24)
文摘The properties of the carbonated brick made of steel slag-slaked lime mixture such as strength, drying shrinkage, water absorption and soundness were mainly investigated. The experimental results indicate that, after carbonation, the strength of the brick increases, its drying shrinkage reduces, and its soundness becomes eligible. The optimal slaked lime/steel slag（SL/SS） ratio for the carbonated brick is 0.2 and the asprepared brick meets the requirements of the Chinese standard for MU20-grade building bricks, additionally, it also demonstrates prominent environmental benefits. The XRD and pore structure analyses indicate that the excellent properties of this carbonated brick are attributed to the formation of carbonate crystals and the dense structure due to the carbonation.
文摘The effect of Ti （ C, N） on properties of low-carbon MgO - C bricks was investigated. The phase composition and the microstructure of the matrix of low-carbon MgO - C brick containing Ti （ C, N） were studied by XRD and SEM analysis together with EDS. The results showed that Ti （ C, N） distributed in the matrix of lowcarbon MgO - C brick uniformly after being treated at 1 600 ~C for 3 h in coke powder bed, and Ti （C, N） and MgO formed a solid solution. After the treatment at 1 600 ℃ for 3 h in coke powder bed, the bulk density and cold crushing strength of low-carbon MgO - C brick with Ti （ C, N） decreased, and the apparent porosity and linear change rate of specimens increased. The oxidation resistance of low-carbon MgO - C brick with Ti（ C, N） was superior to that of low-carbon MgO - C brick with no additives, but inferior to that of low-car- bon MgO - C brick with Al powder. The slag resistance of the specimen with Ti （ C, N） was excellent as well.
文摘The effects of graphite granularity on the properties of low carbon MgO-C based materials have been investigated in the work. Large crystal fused magnesia, natural flake graphite with different particle sizes and anti-oxidant were adopted as raw material for preparation of specimens. However, the results show that the physical properties, oxidation resistance and thermal shock resistance of low carbon MgO-C materials with content of 4.0wt% graphite are improved obviously through the use of special and suitable size graphite. The excellent performance achieved was considered as a result of microstructure modification of MgO-C materials. Therefore, it is suggested that both fine and micro grade natural flake graphite used for production of low carbon MgO-C bricks.
文摘An environmental friendly carbonaceous material- carboresP （one of the Carbores series materials） was investigated for the production of MgO-C refractories in laboratory scale and field tests. The MgO-C specimens were produced with different CarboresP contents. The bulk density （180℃ × 48h）, CCS, apparent porosity （1000℃ ×3h ） and hot modulus of rupture （1400℃ ×0. 5h ） were tested and contrasted. The appropriate amount of carboresP was 1.0%. The amount of metallic additions can be partially substituted （reduced to 1.5% ）. The microstructure of resin-carboresP binder is anisotropic structure with high oxidation resistance and good thermal-shock stability. The Stress/strain curve indicates that the characteristic length, （LCH） of MgO-C brick with resin/CarboresP bonding has been improved, which means the MgO-C bricks have good mechanical flexibility and stresses absorbability. Field tests were done in slag line of a 40t LF-VD refining steel ladle using Resin/CarboresP bonded ＂ MT-14A MgO-C bricks. The result shows that the MgO-C bricks by ＂soft bonding＂ have good physical properties and excellent workability during production of the bricks . In contrast with traditional MgO-C brick used for secondary refining furnaces, the spalling tendency of the bricks could be reduced significantly. The average lining life of the resin/ CarboresP bricks has increased by 18. 4% comparing with the pure resin-bonded types.
文摘Resins PFG-4 , PFG-8 and a reference resin （resin A） were used as binders of MgO - C bricks, effects of the resins with different molecular structures on wettability of magnesia, on physical properties, mechanical properties, oxidation resistance and thermal expansion properties of MgO- C bricks were researched. The results show that the microstructures of solidified resins with different mo- lecular structures are different, which have obvious effect on the cold mechanical properties of MgO - C brick, but little effect on the oxidation resistance, thermal perform- ance and expansion properties.
文摘Properties, section structure and service results of recycled MgO-C bricks and new MgO-C bricks for ladle slag line of Baosteel were analyzed and compared, and the measures of improving stability and quality of recycled MgO-C bricks were summarized. The results show that： （1） High quality recycled MgO-C materials can be produced by scientific, meticulous and strict management for every process such as dismantling furnace, selection, removing impurity and slag, stacking and homogenization ; （2） Using high quality recycled materials and reasonable production technique, recycled MgO-C bricks with better properties and service efficiency than those of new MgO-C brick can be produced; （3） Service efficiency of recycled MgO - C bricks is good because of its high density, good oxidation resistance and reasonable structure.
文摘Hot metal transfer ladles were historically lined with high alumina refractories because of compatibility of high alumina refractories with the highly acidic slag, which is transferred .from the iron making plant along with hot metal. With the introduction of higher capacity ladles, technological advancement in the process and increased productivity, calls for a higher campaign life of hot metal ladles, which could not be performed by ordinary high alumina refractories. Resin bonded Al2O3- SiC-C （hereinafter ASC ） bricks gradually developed which at present taking place replacing the conventional refractories. Considerable work has been carried out in developing the ASC refractory to reach the present state. However, for higher capacity ladles still there is a lot of scope for improvement. The present paper deals with the newly developed ASC bricks, which was used in 165 ton capacity hot metal ladles in one European plant and has given a substantial increase in performance. But, the customer was not fuUy satisfied since the brick was reported to produce smokes during preheating of the ladle. In the subsequent supply the smoke generation problem was taken care by adjusting the binders and additives and eco-friendly bricks were re-engineered and supplied to the same plant, which also performed splendidly and created all time record in their plant history.
文摘Al2O3-SiC-C specimens were prepared using white fused corundum （3-1,≤1 and ≤0.044 mm）,Al2O3-SiC composite powders （d50 ≤ 5 μm）,α-Al2O3 micropowder （d50 =1.2 μm）,SiC powder （≤ 0.044 mm）,flake graphite （≤ 0.088 mm）,Si powder （d50 =42.8 μm） and B4C powder （d50 ≤10 μm） as main starting materials,and thermosetting phenolic resin as binder.4%,8%,12% and 16% （in mass,the same hereinafter） of Al2O3-SiC composite powders substituted the same quantity of α-Al2O3 micropowder ＋ SiC powder.Effects of composite powder additions on apparent porosity,bulk density,cold modulus of rupture,cold crushing strength,hot modulus of rupture （1 400 ℃）,thermal shock resistance （1 100 ℃,water quenching） and oxidation resistance （1 000 and 1 500 ℃） of Al2O3-SiC -C specimens after 180 ℃ curing,1 000 ℃ 3 h carbon-embedded firing and 1 500 ℃ 3 h carbon-embedded firing,respectively,were researched.The results indicate that：（1） with the increase of Al2O3-SiC composite powder,cold strengths of the cured specimens decline,those of the specimens fired at 1 000 ℃ change a little,and those of the specimens fired at 1 500 ℃ change a little except for an obvious improvement of cold crushing strength ; （2） with the increase of Al2O3-SiC composite powder,hot modulus of rupture at 1 400 ℃ decreases and thermal shock resistance enhances significantly; （3） when Al2O3-SiC composite powder addition is 4%,the oxidation resistance at 1 500 ℃ is the best,and the reason may be the composite powder is finer and more active,which is beneficial to form dense mullite protective layer to retard the O2 diffusion into the specimens.
文摘In some steel making workshops, the existed inher- ent weaknesses of traditional carbon containing brick working lining, such as joint opening, vertical cracking of lining, and excessive erosion of brick edge, made it hard to satis]~ the demands of advanced steel produc- tion. A new-type carbon free corundum spinel brick and castable were developed based on the matrix optimized analysis, successfully applied for ultra-low carbon steel production. The advantages of the newly developed car- bon free working lining are mainly as follows： I ） the inherent weaknesses of joint opening, vertical cracking of lining, excessive erosion of brick edge, etc. are sur- mounted successfully, which improves the operational safety of ladles; 2 ） the outer temperature of the ladle shell decreases by 45 -50 ℃ compared with that of the traditional carbon containing brick lining; 3） the service life of new-type working lining is 150 -170 heats, near- ly doubling that of the traditional carbon containing brick lining; the specific eonaumption of refractories per ton steel decreases by about 20% ; 4） the carbon pickup of mohen steel is not obvious which is merely 5 - 10 ppm, which satisfies the demands of low ＆ ultra low carbon steel production.
基金This work was funded by Luoyang Major Science and Technology Innovation Project(2301009A)Henan Province Key ResearchandDevelopment Project(231111230200).
文摘Aiming at improving the properties of magnesia carbon materials,silicon aluminum carbide(Al_(4)SiC_(4))containing materials were prepared using industrial aluminum powder,silicon carbide powder,and graphite as raw materials,and activated alumina powder as an additive,mixing thoroughly,pressing into cylinders and then firing at 1200℃for 30 min in a carbon embedded atmosphere by the microwave method.The effects of the aluminum powder addition(20%and 24%,by mass)and activated alumina powder addition(0,3%,5%and 7%,by mass)on the microwave synthesis of Al_(4)SiC_(4) as well as the effect of the obtained Al_(4)SiC_(4) containing material on the properties of magnesia carbon bricks were studied.The results show that:compared with the samples with 20%aluminum powder,those with 24%aluminum powder generate more Al_(4)SiC_(4).With the activated alumina powder addition increasing from 0 to 7%,the amount of Al_(4)SiC_(4) generated increases first and then decreases.Compared with the sample without activated alumina powder,the samples with activated alumina powder show lower bulk density and higher apparent porosity.With the activated alumina powder addition increasing from 3%to 7%,the bulk density of the samples increases first and then decreases,while the apparent porosity of the samples shows an opposite trend.The optimal additions are 24%aluminum powder and 5%activated alumina powder,and Al_(4)SiC_(4) synthesized in this sample has a hexagonal plate structure.With the synthesized Al_(4)SiC_(4) containing material added,the magnesia carbon brick has slightly increased cold modulus of rupture,basically the same modulus of elasticity and improved oxidation resistance.
文摘The study was conducted to evaluate the changes in soil properties due to the impacts of brick kiln in the vicinity of the Kirtonkhola River, Barisal. The study was carried out by determining the physical, physico-chemical and chemical characteristics of soil. During the entire study period, moisture content of soil ranged from 18.77% to 56.49%;bulk density and particle density varies from 0.23 - 0.53 g/cm3 and 1.11 - 3.15 g/cm3, respectively;soil porosity varies from 60.36% to 88.14%;pH varies from 6.98 to 8.85 and organic carbon content varies from 0.22% to 1.4%. The finding revealed that the pH of the soil decreased with increasing distance from the kiln;moisture content and organic carbon increased with distance;particle density was more or less in ideal condition for plant growth but bulk density and porosity indicates poor soil structure which is unfavourable for plant.
